Tension device



May 5, 1953 J. w. 1. HEIJNIS 7 2,637,511

TENSION DEVICE Filed Oct. 10, 1950 T I M T 5 21 1N VENTOR 1' JMJWMfi'MIM/X W Patented May 5, 1953 TENSION DEVICE James Watt Ijsbrand Hcijnis, Arnhem, Netherlands, assignor to American Enka Corporation, Enka, N. (1., a corporation of Delaware Application October 10, 1950, Serial No. 189,397 In the Netherlands October 17, 1949 4 Claims.

- This invention relates to a device for use in the winding of threads, and more particularly to a device for imparting a constant additive tension to a thread as it is being wound.

In the many various thread handling operations in the textile industry, control of the tension of the thread being handled is generally of considerable importance. To afford tension control for such operations there have been many types of tensioning devices, or thread brakes which are well known in the art. In general, there are two main types-the finger device and the pinch device.

In the finger tensioning device, the thread is conducted over a series of curved surfaces which exert a snubbing action on the thread in accordance with the total angular contact and the coefficient of friction between thread and surface. When the yarn is taken up by a machine at a constant speed from a source that does not produce variations in feed tension, or pretension, such a finger tensioning device functions satisfactorily. In other thread handling operations, however, the yarn is not supplied at an even tension, and in such cases the use of finger tensioning is undesirable, for the variation of tension of the incoming thread is multiplied to give an even greater output tension variation, which often may produce defects such as shiners in a fabric woven from the particular package of thread in which the tension variations occurred.

To overcome this multiplication of tension, the pinch tension device was designed to impart a fixed additive tension to the thread irrespective of the tension of the thread as it approaches the device. In this device, the thread is drawn between two surfaces which are forced together by means such as a spring or weight.

In still other thread handling operations, the thread is not taken up at a constant speed but is collected either at a gradually changing speed, as in the winding of'a cone or tube at constant spindle speed, or at a varying speed, as in the winding of a seriplane board. Both finger and pinch tension devices produce higher tensions at such higher thread speeds.

There are several further problems in the winding of threads with a pinch'tension device. When a twisted-yarn is passed through such a device, the pressure'exerted on the thread by the device tends to cause run-back of the twist. Also, when changing threads, any difference in coefficient or friction between the threads will give dilierent tensioning effects.

2 Another property that a thread tensioning device must have in certain applications is the" ability to prevent the slow passage of thread through the device, called creep, whenever the thread is stopped. This property is especially desirable in warping or creeling, for if it should be necessary to stop the operation for any reason,

such as the rethreading of a broken end,'this creep effect would temporarily lower the tension of the ends being warped, giving rise to undesir able effects.

It is therefore an object of this invention to provide an improved tensioning device of simple construction that can supply an additive pinch tension to a thread being passed therethrough.

It is another object of this invention to provide an improved tensioning device of simple con-, struction that will impart an additive tension to a running thread that is not appreciably affected by the velocity of the thread, by the pretension in the thread, or by the coefficient of friction of the thread.

It is a still further object of this invention to provide an improved tensioning device that will permit the passage of twisted thread without I any run-back of twist.

It is a still further object of this invention to provide an improved tensioning device that is effective in preventing the creep of thread. through the device when the thread has been" stopped under tensions.

other objects and advantages of this invention will become apparent from the following detailed description thereof, when considered in conjunction with the accompanying drawings wherein; Figure 1 is a side view of one embodiment of the device constructed according to this invention;

vice; and

Figure 3 is a vector diagram of the forces actshown, while on the other side of thread lllis located a non-resilient movable shoe I 4, whichis similar in shape to stationary shoe l3. Shoe I4 is rotatably connected by means of hinge pin l5 to an arm I 6, which is rotatably connected to a stationary axle l1, fastened to the frame of the machine by means not shown. A spiral spring Figure 2 is another embodiment of the same de- I A plate-shaped non-resilient I stationary shoe I3 is rigidly positioned on one side of the thread I!) by any suitable means, not I I8 is connected at its central end to axle l1, and at the other end to rotatable arm at point It in such a manner that the action of Spring i8 urges arm 16 in a downward direction, causing movable shoe I4 to bring pressure against thread [0 as it moves upwardly in frictional contact with stationary shoe l3.

Sincearmd G ismounted for pivotal movement about axle ll it can be seen that spring 18 biases arm IS in a clockwise direction as it is viewed in Figure 1.

For efiective operation, both movable shoe M and stationary shoe l3 should be champiered or rounded off at the ends in the manner shown in the drawing. For even distribution of pres sure by movable shoe M, it is necessary that hinge pin H: be located centrally of the shoe.

It will be noted that the arm Iii, asshownin Figure 1, lies at an angle to a plane normal to the path of thread travel between the aligned goddess and 1.2. The plane normal to the thread path .is designatedasA and the angle defined between ithatplane and the arm is s desi natedas la The shoe it is not shown in its,;..position of maximum proximity to the shoe 13. but .is biased toward that position by the springiB. .Thus the shoe hi is capable of movementbothcloser to and Lfurther from the shoe l.3.to..vary.-the pinch applied to the thread. As aniimportant part of thisinvention the friction between the thread and the shoes is effective to controlitherelative position of the shoes and the pressure of the pinch applied thereby.

In operation, the functioning of this device is extremely simple. For-understanding the action 0f,it,fit.'is necessary to refer briefly to the effect upon thencoefilcient of friction between a runningthread and a tensioning device with various conditions of thread velocity. When a pinch device similar to that described above, but'lackingjin the movable arm mechanism, is used to tension a'thread,it has been" found that, with a constant load upon the two tensioning elements, the output tension of'the device is far'irorn constant. -As. theithread speed is increased with a constant pretension,'the output tension increases fairly regularly, although not linearly. Since the load upon the 'tensioning device is constant, the only explanation 'for'this increase in tensioning canbe' the increase in the-coefficient of friction between-threadand device. This maybe rather difilcult to explain in light "of the usual concept of "coeilicientofpfriction, so that hereafter this coefficientof friction will be interpreted as meaninggthe'degree of frictioning coupling,'or effective *coefiicient of friction between thread and device;

The device of the present invention utilizes changes in the efiective coeflicient of friction to adiust the loading 'force exerted upon the .two elements of the tensioning device in such a man nenthat as the coefficient of friction increases, the loading force decreases, thereby giving a "balancingaction.

This balancing action will be more readily understoodby referring in greater detail to Figure,.3, which represents the forcesacting upon single point of the movable shoe of the device of-thepresent invention as described above.

The point which will be used in this vector analysis willbe a point onthe surface of movablezshoe ;-l4 immediately underneath hinge pin l5,,.which point will be considered to-bea free body The spring l8 which urges movable shoe. l4 bothto' the right asshown inFigure 1, against thethread and downwardly counter to ,the. dir ec.- ,75;

4 tion of thread travel, has an effect which can be represented by two corresponding vector forces, l-N, tending to move the free body to the right, and tending to move the free body downwardly. The force Fit, by the basic laws of mechanics must be opposed by an equal and 0pposite force .F'r. The vector FT, in turn, may be resolved into two equivalent vector forces. FA, acting along movable arm I6, and FE acting parallel to the direction of thread travel. As

shown in Figure 3, the vector sum of FA and Fe isnumerically equal to Fr.

The drag between the thread surface and the movable shoe surface is dependent upon the ,efiective coeflicient of friction and the magni- Considering now the three'forces'acting'ln the direction of thread travelyan equilibrium'must exist as follows:

FH=FF+EB 3).

The equations 'of FF andFBfrom '(1) and ,(2) respectively can nowbesubstituted in Equation 3, which thus becomes- FH=MFN+tan aFJv which can then be revised to give Theitotal tension .8, whichisimpartedto'the thread, W11]. obviously be twice .the 'dragexerted by each shoe, or,

-S=. 2FF

but since from Equation 1 'FF=./.LFN

S =2;1FN

Substituting the value :of Fm from Equation vi into ,5 thengivesthe equation tan a i p.

Assuming now that 'tan ..a. has :a -smallwah1e and that ,u. is,.increased,-it-can be seen rthatiin the .above equation, the numerator contains tending: to. give atension; increase that is: propertional to the increase in i. Therdenomhlatnr; however, consists-of the .-sum of anda-small constant, so. that if ,LL increases, :the denominator. also .mcreases, but. not in .a linear .manner.

keeping .tan .a small. as. .compared=- o: thevvalue'nr "the increasein the .valueof the. denominator s nearly linear, and therefore, i the --e ffect enlarge;- mcreasesin isto, give onlya slight.- rise; of, output -,tension S. I

This can also be shown in another manner. by rearranging Equation 6 to give In this instance, by keeping tan a. small, it can be seen that large variations in ,u are dampened, and thus the sum of the constant 1 and the fraction tan a is relatively constant.

The embodiment disclosed in Figure 1 depicts the basic principles of this invention. A further modification is shown in Figure 2, in which a positioning ring 20 is fastened about axle H to enable adjustment of the spring tension by means of clamp 2|, which adjustably connects spring l8 to ring 20. A connecting chain 22 is provided to transmit the action of spring l8 to movable shoe [4 at hinge pin I5. If higher or lower tensions are desired, clamp 2| can be adjusted in either a clockwise or counter-clockwise direction respectively on positioning ring 20. In this manner, the tension of the thread as it leaves the device can be very easily adjusted.

Other means can be used to load arm l6 than the spring 18. For example, a weight can be suspended from the arm, or other types of springs with or without supplementary adjustable weights can be employed.

Further flexibility can be obtained if the distance of the fixed axle ll from stationary shoe l3, or if the length of rotatable arm [6 is made adjustable. The length of arm l6 should be relatively great in comparison with the thickness of the thread, for in this manner small variations in the thickness of the thread being wound produce relatively small deflections of movable shoe l3, which in turn produce small variations in the angle a. As long as these angular variations remain small, the necessity for adjusting the separation of fixed axle I! from the stationary shoe l3, or the length of arm I6 is often eliminated.

When an irregularity, such as a fluff, occurs in the running thread, which could give rise to an increased tensioning, the shoe gives way easily. As compared to earlier pinch type tensioning devices, the device of the present invention also possesses the feature that if the thread should be broken between tensioning device and collection package, the device will clamp the thread in position to facilitate subsequent rethreading operations.

By champfering or rounding off the ends of the two shoes, and by using shoes which are relatively long, the pressure on the thread at any given point can be small, even though the total force between shoes and thread may be high. This low pressure on the thread effectively prevents run-back of twist, even when highly twisted yarns, such as crepe yarns, are wound. If it is desired to gradually increase or decrease the pressure on the thread as it passes through the tensioning device, hinge pin I5 can accordingly be located out of center of shoe I4.

A further advantage resulting from this low pressure on the thread resides in the relatively small amount of wear or cutting-in of the running thread on the shoe surfaces. This cuttingin has been a problem in earlier pinch devices, which in some instances have overcome it by utilizing traversing mechanisms toprevent the threadfrom following any one continual line of travel through the tensioning device. Such mechanisms arenot needed in this invention.

In operation, when the angle a is less than 10, and preferably about 5, the drag imparted by the two pinching shoes is practically independent of the coefficient of friction between the thread and the shoes. It is desirable to use the same material for both shoes, using polished steel or any other suitable material. When the angle a. is about 5, it has been found that the increase in tension imparted by this device to the thread is practically independent of the speed of the pretension in the thread. Creep-through, when the thread is stopped, is practically eliminated by the use of this device.

It is understood that this invention is not intended to be limited to the embodiments given in the foregoing description, but only to the extent of the appended claims.

What is claimed is:

1. A thread tensioning device comprising spaced guides defining a thread path therebetween, a fixed elongated fiat rigid tensioning shoe presenting a surface parallel and contiguous to the thread path, a movable elongated flat rigid tensioning shoe presenting a surface contiguous to the thread path, a pivot arm mounting said movable shoe for arcuate movement in a plane parallel to the thread path and perpendicular to the surface of the fixed shoe toward and away from said stationary shoe from a normal position slightly away from the position of maximum proximity of said shoes, said arm being inclined about a stationary axle perpendicular to said plane in such a manner that an angle of between zero and ten degrees is formed between said arm and perpendicular from said axle to said stationary shoe, said movable shoe being closer to the output thread guide than to the input thread guide, and means to bias said movable shoe toward said position of maximum proximity.

2. A thread tensioning device comprising a pair of elongated fiat tensioning shoes coacting to pinch therebetween a thread being passed along a path defined by two spaced line guides, one of said shoes being stationary and parallel and contiguous to the surface of said thread path, the other shoe being movable and pivotally connected at its center to an arm, said arm lying in a plane containing the thread path and perpendicular to the surface of said shoes, and being rotatably connected about a stationary axle perpendicular to said plane, and inclined towards the output thread guide so as to form an angle of between zero and ten degrees with a perpendicular from said stationary axle to said stationary shoe, and means for yieldingly urging said movable arm in a direction to cause said movable shoe to tend to move arcuately counter to the direction of the thread and against said stationary shoe.

3. A thread tensioning device comprising a pair of fiat tensioning shoes coacting to pinch therebetween a thread being passed along a path defined by two spaced thread guides, one of said shoes being stationary and parallel and contiguous to the surface of said thread path, the other shoe being movable and pivotally connected to an arm, said arm lying in a plane containing the thread path and perpendicular to the surface of said shoes, and being rotatably connected about an axis perpendicular to said plane, and inclined so as to form an angle not greater than 10 with a perpeneieuiar from Sam axis to said stationary Shoe, and means fb't yiel'dmsiy urging said ar-m iiia dii-etion to pause said movable shoe to tend 50 move arcuateiy counter to the direction of the thread and against said stationary shoe.

4. A thread t'tlsib'hiiig device oompi isih'g' "spaced g'ui'des defining a thread path therebetween, a fixed elon'g ated fl'at rigid temsioh'ing shoe presenting a surface parallel and contiguous to the thread path, a movable elongated fiat rig-id th'sibhiki'; shoe presenting sear-face contiguous to the thread path, eaeno'f said shoes having bevelled edges at the ends thereof, a pivot arm connected to the center of said movable shoe mounting said' movabie shoe for arm-ate movement in a plane par-enema the thread path and perpehdioular to the stir-face or the i flxed Shoe toward and away from said stationary "shoe 8 from a normal position slightly away from the position of maximum proximity of said. shoes. said arm being inclined about a stationary axle perpendicular to said plane in such a manner that an angle of between 0 and 10 is formed between said arm and a perpendicular from said axle to said stationary vshoe, said wmovable shoe being closer to the output thread guide than to the input thread guide, and adjustable means to bias said movable shoe toward said position of maximum proximity.

JAMES W A'IT IJ SBRAND HEIJNIS.

References Cited in the file of this patent UNITED STAT-ES PATENTS Number 'Name Date v 1365363 Abbott July 3, 1934 2,209,839 Long 3. July 30, I940 

